N,n&#39;-dialkyl-phenylenediamine-biguanide and use as additive in non-aqueous substrates

ABSTRACT

N1-(P-ALKYLAMINOPHENYL)-N1-ALKYBIGUANIDE AND USE AS ADDITIVE IN NONAQUEOUS SUBSTRATES. THE INVENTION IS EXEMPLIFIED BY N1-(P-SEC-OCTYLAMINOPHENYL)-N1-SEC-OCTYLBIGUANIDE AND THE USE THEREOF AS AN ANTIOXIDANT, CORROSION INHIBITOR AND/OR ANTI-ICING COMPOUND.

United States Patent 3,553,263 N,N' l)IALKYL-PHENYLENEDIAMINE-BIGUA- NIDE AND USE AS ADDITIVE IN NON- AQUEOUS SUBSTRATES Robert H. Rosenwald, Western Springs, and Earl A. Nielsen, Lombard, Ill., assiguors to Universal Oil Products Company, Des Plaines, III., a corporation of Delaware No Drawing. Filed Dec. 20, 1967, Ser. No. 691,993 Int. Cl. C07c 129/100 US. Cl. 260-565 6 Claims ABSTRACT OF THE DISCLOSURE N -(p-alkylaminophenyl)-N -alkylbiguanide and use as additive in nonaqueous substrates. The invention is exemplified by N -(p-sec-octylaminophenyl)-N -sec-octylbiguanide and the use thereof as an antioxidant, corrosion inhibitor and/ or anti-icing compound.

DESCRIPTION OF THE INVENTION The novel biguanide derivative of the present invention may be illustrated by the following general formula:

I G i I f RN N-(|?N?|3NR N-H N-H where R is alkyl of at least 6 carbon atoms and R is hydrogen or alkyl.

In a particularly preferred embodiment, R is sec-alkyl of at least 6 carbon atoms and more particularly of 6 to 20 carbon atoms and R is hydrogen. Illustrative preferred compounds include N (p-sec-hexylaminophenyl-N -sec-hexylbiguanide,

N (p-sec-heptylaminophenyl -N -sec-hepty1biguanide,

N (p-sec-octylaminophenyl) -N -sec-octylbiguanide,

N -(p-sec-nonylaminophenyl)-N -sec-nonylbiguanide,

N p-sec-decylaminophenyl) -N -sec-decylbiguanide,

N -(p-sec-undecylaminophenyl) -N -sec-undecylbiguanide,

N -(p-sec-tridecylaminophenyl)-N -sec-tridecylbiguanide,

N (p-sec-tetradecylaminophenyl -N -sec-tetradecy1- iguanide,

N -(p-sec-pentadecylaminophenyl)-N -sec-pentadecylbiguanide,

N (p-sec-hexadecylaminophenyl) -N -sec-hexadecylbiguanide,

N (p-sec-heptadecylaminophenyl) -N -sec-heptadecylbiguanide,

N (p-sec-octadecylaminophenyl -N -sec-octadecy1- biguanide,

N (p-sec-nonadecylaminophenyl) -N -sec-nonadecylbiguanide and N -(p-sec-eicosylaminophenyl)-N -sec-eicosylbiguanide.

While the sec-alkyl substitutions are preferred, in another embodiment, these may be n-alkyl or tertiary-alkyl. While it generally is preferred that both of the R substituents are of the same configuration and chain length, it is understood that these may be of different chain length and/ or of different configuration but, as hereinbefore set forth, each will contain at least 6 carbon atoms.

Referring to the above general formula, when R attached to the left hand nitrogen is alkyl, the novel compound will be N (p-dialkylaminophenyl) N alkylbi guanide, the alkyl designated by R being selected from those hereinbefore set forth. The alkyl designated by R may be the same as R or it may be an alkyl containing from 1 to carbon atoms. Where R attached to the right hand nitrogen in the above general formula is alkyl, the compounds will be selected from N (p alkylaminophenyl)-N -alkyl-N -alkylbiguanide. Here again the R and R groups will be selected from those hereinbefore set forth.

It is an essential feature of the present invention that the R substituents are alkyl groups of at least 6 carbon atoms each. As will be hereinafter set forth, these compounds are useful as additivesin nonaqueous substrates and, therefore, must be oil soluble and substantially water insoluble. In many cases, the oil substrate may have water entrained therein or may contact water, either intentionally or accidentally, and the additive should not be soluble in the water and removed from the oil with the water.

The novel compounds of the present invention are prepared in any suitable manner. In a preferred method, N,N' dialkyl-p-phenylenediamine or N,N,N'-trialkyl-pphenylenediamine is reacted with dicyandiamide. More particularly, the N,N-dialkyl-p-phenylenediamine is dis solved in a suitable solvent and reacted with mineral acid and particularly concentrated hydrochloric acid to form the hydrogen chloride salt. An alcohol solvent is particularly preferred and can be selected from methanol, ethanol, propanol, butanol, pentanol, hexanol, etc. Other solvents may include water or aromatic hydrocarbons such as benzene, toluene, xylene, cumene, etc. At least 1 mol of dicyandiamide is employed but generally advantages appear when the dicyandiamide is used in excess which may range from 1.5 to 6 and generally from 2 to 4 mol proportions of dicyandiamide per one mol proportion of the disubstituted p-phenylenediamine. The dicyandiamide is added at a temperature between and F. The mineral acid generally will be used in a concentration of from 1 to 2 mol proportions thereof per 1 mol proportion of the p-phenylenediamine and is added'at a temperature below 140 F. by cooling as necessary. When desired, the system may be nitrogen blanketed to minimize oxidation. The reaction is effected at a temperature of from about to about 350 F., preferably from about 200 to about 300 F., for a sufiicient time to insure completion of the reaction. The time of reaction will vary with the reaction temperature and generally will be in the range of from about 0.5 to about 12 hours and preferably from about 1 to about 6 hours. The temperature and time will be correlated to avoid excess time at high temperature which may result in decomposition of the dicyandiamide or the reaction product.

Following completion of the reaction, the product can be worked up in any suitable manner. In general, this includes neutralizing with a suitable base such as alkali metal hydroxide, particularly sodium hydroxide, potassium hydroxide, or with ammonia, etc. The reaction mixture then is dissolved in ether or other solvent, water washed, filtered, etc., as required to recover the final product. Generally the product will be recovered as a viscous liquid and may be utilized as such or formed as a solution in an oleaginous solvent.

The novel compound of the present invention is used as an additive in various nonaqueous substrates. Accordingly, as hereinbefore set forth, it is essential that the additive is soluble in nonaqueous substrates in order that the additive may be satisfactorily incorporated and retained in the substrates. In one embodiment, the additive serves as an antioxidant to retard deterioration of the substrate due to oxidative reactions. A specific example in this embodiment is rubber in which the additiveserves to retard oxidative deterioration of the rubber. Other solid or semisolid substrates include plastics, resins, adhesives, etc. The plastics are of varied types including polyolefins as polyethylene, polypropylene, polybutylene and mixed polymers of ethylene-propylene, ethylenebutylene, propylene-butylene, ethylene-propylene-butylene, etc., and/or polymers of higher molecular weight olefins. Other plastics include polystyrene, vinyl resins derived from monomers as vinyl chloride, vinyl acetate, vinylidine chloride, etc., and particularly polyvinyl chloride and copolymers of vinyl chloride with acrylonitrile with methacrylonitrile, various alkyl acrylates, methacrylates, rmaleates, fumarates, etc., ABS (acrylonitrilebutadiene-styrene polymer), polyurethanes, both foam and rigid, epoxy resins, polycarbonates, phenol formaldehyde resins, urea formaldehyde resins, etc.

Another nonaqueous substrate is grease which may be of natural or synthetic origin. The metal base synthetic greases include lithium grease, sodium grease, calcium grease, barium grease, strontium grease, aluminum grease, mixed base greases, etc., which generally are prepared by adding to natural or synthetic lubricating oil, one or more hydrocarbon soluble metal soaps or salts of higher fatty acids as, for example, lithium stearate, calcium stearate, aluminum naphthenate, etc., and which also may contain various additional thickening agents such as silica, carbon black, talc, etc.

Nonaqueous liquid substrates include hydrocarbon distillates such as gasoline, naphtha, kerosene, jet fuel, diesel fuel, fuel oil, lubricating oil, etc. The lubricating oil may be of natural origin or synthetically prepared. The natural lubricating oils include those of petroleum origin and referred to as motor lubricating oil, marine oil, transformer oil, turbine oil, differential oil, diesel lubricating oil, gear oil, cylinder oil, etc., or it may be of animal, marine or vegetable origin.

Synthetic lubricating oils are of varied types including aliphatic esters, polyalkylene oxides, silicones, esters of phosphoric and silicic acids, highly fiuorinated hydrocarbons, etc. Illustrative examples include alkyl sebacates and particularly di (2-ethylhexyl) sebacate, dialkyl azelate, dialkyl suberates, dialkyl pimelates, dialkyl adipates, dialkyl glutarates, etc. Still other synthetic lubricating oils include neopentylglycol esters, trimethylol alkanes, tricresol phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, as well as mixed aryl and alkyl phosphates. The natural and synthetic lubricating oils also are used as cutting oils, rolling oils, soluble oils, drawing compounds, slushing oils, etc.

In the above uses, the additive serves primarily as an antioxidant. The novel compound of the present invention also possesses corrosion inhibiting properties and thus may be used for this purpose in nonaqueous substrates contacting metal parts which undergo such corrosion.

In still another embodiment, the compound of the present invention also possesses anti-icing properties and thus the additive may be used in gasoline or the like to retard icing formation in carburetors and thus avoid stalling of the engine. Such stalling is encountered under idling or low load conditions during periods of high humidities and temperatures ranging from about 30 to about 60 F.

The concentration of the compound of the present in vention to be employed as an additive will depend upon the particular substrate in which it is to be used. This may range in concentration of from about 0.0001% to about 25% by weight of the substrate and more particularly within the range of from about 0.0001% to about 5% by weight of the substrate.

It is understood that the additive of the present invention may be used along with other additives incorporated in the nonaqueous substrate. This will vary with the particular substrate and could include, for example, the use of an antiozonant in rubber, the use of a viscosity index improver, pour point depressor, antifoam additive, detergent, etc., in lubricating oil, or a metal deactivator, antiknock agent, dye, etc., in gasoline.

The following examples are introduced to illustrate further the novelty and utility of the present invention but not with the intention of unduly limiting the same.

4 EXAMPLE 1 This example describes the preparation of N -(p-secoctylaminophenyl) N -sec-octylbiguanide. The preparation was made by adding, with stirring, 200 ml. of nbutanol to 166 g. (0.5 mol) of N,N'-di-(2-octyl)-pphenylenediamine and then gradually adding thereto ml. (1 mol) of concentrated hydrochloric acid, the temperature being kept below 140 F. by cooling. This resulted in the precipitation of solid and the formation of a thick slurry. Then 42 g. (0.5 mol) of dicyandiamide was added at a temperature between and F., the mixture becoming a homogeneous solution. The mixture was warmed to 248 F. and maintained at this temperature for 2 hours with continued stirring. The mixture was cooled and 200 ml. of water was added, followed by the addition of 44 g. (1.1 mol) of sodium hydroxide in 100 ml. of water, with continued stirring. Then about 1000 ml. of ethyl ether was added, and the mixture separated into an aqueous phase and an organic phase. The organic phase was washed with 200 ml. of water and dried over sodium hydroxide and potassium carbonate. The aqueous phase was washed with 200 ml. of ether and the ether phase was combined with the organic phase prior to said drying. The organic phase was filtered and the solvent removed from the filtrate by vacuum distillation. N -(p-sec-octylaminophenyl) N sec-octylbiguanide was recovered as the dried product in a yield of 209 g. as a red brown viscous liquid.

EXAMPLE H The compound of this example is the same as Example I and was prepared in substantially the same manner as described in Example I except that the reactants were used in amounts of 83 g. (0.25 mol) of N,N'-di-(2-octyl)- p-phenylenediamine, 43 ml. (0.5 mol) of concentrated I-ICl, 84 g. (1 mol) of dicyandiamide and 200 ml. of nbutanol. The reaction was affected at 248 F. for 2 hours and followed the work up procedure as described in Example I. The desired product was recovered in a yield of 92 g. as a viscous liquid. Total nitrogen (Dumas) was found to be 19.81 which corresponds to the theoretical nitrogen content of 20.2 for N (p-sec-octylaminophenyl)- N -sec-octylbiguanide.

It will be noted that in this example the dicyandiamide was used in a mol proportion of 4:1 to the disubstituted phenylenediamine. The use of the excess appears to facilitate the reaction.

EXAMPLE III The compound of this example is N -(p-l-ethyl-3- methylpentylaminophenyl) N l-ethyl-3-methylpentylbiguanide and is prepared in substantially the same manner as described in Example II except that the disubstituted phenylenediamine used as the reactant is N,N'-di- 1-ethyl-3-methyl pentyl) -p-phenylenediamine.

EXAMPLE IV The compound of this example is N -(p-sec-hexylaminophenyl)-N -sec-hexylbiguanide and is prepared in substantially the same manner as described in Example II except that the phenylenediamine reactant is N,N-di- (l-ethylbutyl)-p-phenylenediamine. The product is recovered as a viscous liquid.

EXAMPLE V The compound of this example is N -(p-l,4-dimethylpentylaminophenyl)-N -1,4-dimethylpentylbiguanide and is prepared in substantially the same manner as described in Example II except that the phenylendiamine reactant is N,N' di (1,4-dimethylpentyl)-p-phenylenediamine. Here again the product is recovered as a viscous liquid.

EXAMPLE VI The compound of this example is N -(p-sec-dodecylaminophenyl)-N -sec-dodecylbiguanide and is prepared in substantially the same manner as described in Example II except that the phenylenediamine reactant is N,N'-di-secdodecyl-p-phenylenediamine.

EXAMPLE VII The compound of this example illustrates the compound in which R attached to the right hand nitrogen of the foregoing formula is alkyl. The compound prepared as described in Example II is reacted with butyl chloride at a. temperature of about 165 F. The resulting product is N -(p-sec-octylaminophenyl)-N -sec-octyl N n butylbiguanide.

EXAMPLE VIII This example illustrates the use of the N -(p-sec-octyl aminophenyl) N sec-octylbiguanide, prepared as described in Example II, as an antioxidant in rubber. The rubber used in this example was of the following formula:

1 N-cyclohexyl-2-benzothiazole-sulfenamide.

The parts by Weight are on the basis of the rubber hydrocarbon and are so used in the present specifications and claims. The rubber formulation was cured for 40 minutes at 284 F.

Different samples of the rubber were evaluated by suspending dumbbell specimens in a glass tube through I which air was passed at 194 F. The percent ultimate elongation, 200% modulus and tensile strength, originally and after 1, 2, 4 and 7 days of exposure to air at 194 F., are reported in the following table.

These results include those for control samples of the rubber not containing an additive and for samples of the rubber containing 3% by weight of the compound of the present invention, prepared as described in Example II. For convenience, the control samples (not containing the additive) are designated by A and the samples containing 3% by weight of the additive of the present invention are designated by B.

Referring to the data in the above table, it will be seen that the physical properties of the rubber were considerably improved by use of the additive of the present invention.

EXAMPLE IX This example describes the use of a compound of the present invention as a corrosion inhibitor. The corrosion inhibiting properties were determined in accordance with ASTM D655IP135 method using iso-octane and synthetic sea water. The test was continued for 5 hours. In general, this method comprises suspending a steel test specimen in a beaker equipped with a stirring device and heating the same by means of an oil bath to a temperature of about F. The test specimen is then rated as either passing or not passing the test.

N -(p-sec-octylaminophenyl) N sec-octylbiguanide, prepared as described in Example II, in a concentration of 30 parts per million resulted in passing of the test solution evaluated in the above manner. This demonstrates the corrosion inhibiting properties of the compound of the present invention.

EXAMPLE X This example illustrates the use of a compound of the present invention as an anti-icing additive in gasoline. The compound used in this example is N -(p-sec-octylaminophenyl)-N -sec-octylbiguanide, prepared as described in Example I.

The anti-icing properties were determined in a carburetor icing demonstrating apparatus consisting of a vacuum pump equipped so that cool moisture-saturated air from an ice tower is drawn through a carburetor. The gasoline sample passes from a fuel reservoir through a flow meter into the carburetor at a rate of 14.4 lb./hr. The air from the ice tower is passed at a fiow rate of 14.4 lb./hr. at a temperature of 40 F. The manifold vacuum is 9:5 in. Hg at the start and 12.5 in. Hg at the end of the test. Evaporation of the gasoline in the carburetor further cools the cold moist air, with resulting ice formation on the throttle plate. The time in seconds is measured until a drop of 3 in. Hg vacuum occurs, which indicates stalling conditions.

The fuel used in this example is a commercial gasoline which, without the additive of the present invention, reached stalling conditions within 7.7 seconds.

In contrast, a sample of the gasoline containing 25 parts per million of N -(p-sec-octylaminophenyl) N -secoctylbiguanide, prepared as described in Example I, did not reach stalling conditions until 14.5 seconds. This demonstrates the anti-icing properties of the compound of the present invention.

We claim as our invention:

1. A compound of the formula Where R is alkyl of 6 to 20 carbon atoms and R is hydrogen or alkyl of 1 to 5 carbon atoms.

2. The compound of claim 1 being N -(p-sec-heptylaminophenyl) -'N -sec-heptylbiguanide.

3. The compound of claim 1 being N -(p-sec-octylaminophenyl) -N -sec-octylbiguanide.

4. The compound of claim 1 being N -(p-sec-decylaminophenyl)-N -sec-decylbiguanide.

5. The compound of claim 1 being N -(p-sec-dodecylaminophenyl) -'N -sec-dodecylbiguanide.

6. The compound of claim 1 being N -(p-alkylaminophenyl)-N -alkyl-N -alkylbiguanide in which the alkyl of the p-alkylaminophenyl group and the N -alkyl contain from 6 to 20 carbon atoms each, and the N -alkyl group contains from 1 to 5 carbon atoms.

References Cited UNITED STATES PATENTS 2,422,88'8 6/1947 Curd et al. 2-605'5 1 BERNARD HEL-FIN, Primary Examiner G. A. SCHWARTZ, Assistant Examiner US. Cl. X.R. 252-401, 390, 77 

